Psychrophilic Quorum Sensing Genes Enable Unimodal, Adjustable Protein Expression Across the Entire Escherichia coli Population.

Abstract

A previous study demonstrated that quorum sensing (QS) genes from the psychrophilic bacterium Aliivibrio logei can be used in Escherichia coli to obtain bacterial cultures with controlled amounts of a target protein. However, the QS system may be induced non-uniformly across the cell population. In this study, we used an expression vector containing luxR/luxI regulatory genes from A. logei carrying sfGFP as a reporter gene. Reporter expression was regulated by the autoinducer 3OxoC6-HSL, activated at 22 °C, and terminated at 37 °C. Flow cytometry was used to assess the GFP fluorescence distribution at the single-cell level. The system provided dose-dependent unimodal expression lacking formation of distinct ON/OFF subpopulations, while the robust coefficient of variation decreased with increasing autoinducer concentration. The autoinducer synthase LuxI enabled autoinduction, but under the tested conditions, no substantial effect on expression homogeneity was detected. Raising the temperature to 37 °C effectively halted expression, allowing intermediate target protein values to be fixed at the single-cell level. Overall, the developed system represents a promising tool for biotechnological applications requiring precise and uniform control of expression.